There are a number of water generating machines described in the art which employ conventional dehumidifiers for removing water from the air for collection into a storage tank. Many machines also employ various types of water and air filtration systems to create water that is safe to drink. While current water producing machines may operate satisfactorily indoors at room temperature conditions, they are not particularly conducive for use outdoors, especially at lower temperatures. In situations where it is desirable to operate the water producing machine outdoors, many if not all of these machines will be inoperable at cooler temperatures.
In military applications, for example, it is particularly desirable to have a potable water producing machine readily on-hand. Each soldier requires a minimum of about a gallon of water per day under battle conditions. Water is not only necessary for drinking purposes, but many food rations are dehydrated, requiring the addition of water prior to consumption. Moreover, in certain areas, water may be scarce or not safe for consumption, thus requiring the transport of fresh water in the field. However, carrying fresh water at about 8.3 pounds/gallon can be difficult to carry and transport. Having the ability to produce water on-site or on a moving vehicle could overcome the logistical problem of distribution.
Generally, during military training expeditions or in actual military actions, military personnel are required to camp outdoors. Under such conditions, it is especially beneficial to have a water producing machine that will operate at outdoor temperatures as low as 50.degree. F., as may be readily encountered in certain regions. Moreover, it is especially important in military applications to have all supplies and equipment, including the water producing machine, to be readily and quickly transportable under rigorous conditions, including air drop deliveries. It is also desirable that the water generating machine be capable of operating from the electrical system of a military vehicle.
The present invention is a potable water producing and dispensing machine that incorporates one or more improvements over the prior art that make the machine particularly conducive for use outdoors, especially in outdoor military applications. While the most preferred embodiment of the present invention employs all of the novel features described and illustrated herein, it will be appreciated by the skilled artisan that the present invention is broader than the most preferred embodiment, and thus may incorporate only one or more of the improved features, as described and claimed herein.
In general, the present invention comprises (a) a housing unit having an air outlet and an air inlet; and (b) a dehumidifier system disposed within the housing unit between the air inlet and outlet. The dehumidifier system comprises an air blower that draws ambient air into the housing unit via the air inlet and through the dehumidifier system. The dehumidifier system may be any conventional dehumidifier system that is capable of removing water from ambient air. A conventional dehumidifier system comprises an evaporator, a compressor pumping a refrigerant gas, a condenser, and an air blower. In the preferred embodiment of the present invention, the dehumidifier system is designed to remove water from ambient air drawn into the housing unit through the air inlet as ambient air moves over the evaporator surface and condenses thereon as water droplets. The inventive machine further includes a water containment tank in communication with the evaporator and disposed within the housing unit. The tank is structured to receive and store the water droplets from the evaporator.
Additional aspects of the inventive machine include a novel water dispensing and filtration system disposed within the housing unit and which is in communication with the water containment tank. The water dispensing and filtration system further comprises (a) a water delivery tube having one end positioned within the water containment tank to remove water from the tank and a second end in communication with a spigot; (b) a water pump connected to the water delivery tube; (c) at least one water filter in communication with the water delivery tube; and (d) a water return tube having one end positioned within the water containment tank and a second end in communication with the water delivery tube; whereby when the water pump is activated and the spigot is closed, water is drawn from the water containment tank, carried through the water delivery tube and water filter, and then through the return tube and back into the water containment tank. The water dispensing and filtration system further includes a dispensing switch for opening and closing the spigot via a valve connected to the spigot. When the dispensing switch is activated to open the valve, water contained and moving through the water delivery tube is diverted from the water return tube and dispensed through the spigot. When the dispensing switch is activated to close the valve, the water continues to flow from the water delivery tube through the return tube and to the water containment tank. Preferably, the return tube has a narrow diameter near the end positioned within the water containment tank, thereby further causing the water to be diverted from the return tube to and though the spigot upon activation of the dispensing switch to open the valve. These aspects of the invention allow for continuous water filtration prior to dispensing, thereby minimizing, if not eliminating entirely, the risk of water stagnation within the water containment tank during long periods of non-use.
Other aspects of the present invention include a novel construction of the housing unit that protects the interior contents of the machine from damage during very rigorous handling and transportation. Preferably, the housing unit incorporates an exoskeletal frame formed of a strong metal that provides an extremely durable enclosure. The side panels, top and bottom panels, and end panels may be formed of a durable material, such as steel or aluminum, to encase the interior contents. The provision of a such a rugged enclosure is particularly desirable in military applications, where it may be necessary at times to air drop the machines from airplanes or helicopters to desired locations or to load over truck sides. Without some means of protecting the machines from damage during these deliveries, the machines would be severely damaged upon falling. The outer frame of the present invention solves this problem, and allows air drop deliveries of the machines by parachute.
The present invention, in certain embodiments, may also include a novel hot gas injection system that functions to prevent condensate from freezing on the evaporator surface, and thereby continue operation, at temperatures of about 20.degree. F. below ambient. This feature is particularly desirable for use at low outdoor temperatures, where freezing of the evaporator presents a problem. As discussed above, conventional dehumidifiers as well as water producing machines of the prior art are only designed to produce water in an air-conditioned environment. That is, such ambient conditions are generally 75-78.degree. F., with relative humidity of about 45-55%. However, in outdoor settings, where substantially cooler ambient temperatures may be as low as 50.degree. F., the evaporator surface temperature, which is operating at 20.degree. F. below ambient (i.e. 30.degree. F.), will generally freeze. Thus, the hot gas injection system is designed to increase the evaporator temperature by about 4 to 5.degree. F., thereby preventing the condensate on the evaporator surface from freezing while still maintaining the evaporator temperature below its dew point in order to operate properly (i.e. remove water condensate from the ambient air entering the housing).
The hot gas injection system of the present invention comprises a hot gas bypass tube in communication with the refrigerant gas tube of the compressor and the refrigerant liquid tube extending from the condenser. The injection system further include a hot gas solenoid valve disposed within the bypass tube and a thermostat with a temperature sensor, the sensor positioned on the evaporator. The thermostat, which is in electrical communication with the hot gas solenoid, is programmed to a predetermined evaporator fin temperature, generally about 34.degree. F., at which point it will trigger the solenoid valve to open, thereby releasing a limited metered amount of hot refrigerant gas from the compressor to the refrigerant liquid tube into the evaporator inlet via the bypass tube. The consequent mixture of the hot gas with the refrigerant liquid contained within the refrigerant liquid tube increases the temperature of the refrigerant liquid prior to entering the evaporator. This feature prevents condensate on the evaporator surface from freezing, thereby allowing continued operation of the machine by increasing the evaporator fin temperature. The thermostat may also be programmed to a second predetermined temperature that is lower than the first pre-determined temperature to deactivate the dehumidifier system of the machine when even colder, generally freezing, conditions of the ambient air entering the evaporator.